Study of axial fan grilles noise and aerodynamic characteristics

摘要

Axial fan grilles influence aerodynamic and noise characteristics in the complete operating range. The local outflow velocity field of the fan without grill at the optimal operating point was measured using a direction velocity probe and the measurement results were used to model an optimised grill contour. Presented are results of measurements of aerodynamic integral characteristic, sound power level and sound pressure level spectrum. Three axial fan modifications were studied, fan without grill, fan with original grill, and fan with optimised grill. At the optimal operating point fan without grill has 18% better efficiency than fan with standard grill, and 15% better efficiency than fan with optimised grill. Influence of grill is reflected also in sound power level of compared fans. At the optimal operating point fan without grill has 4 dBA lower sound power level than the fan with standard grill, and 2 dBA lower sound power level that the fan with optimised grill.